Abstract
Six avian reovirus isolates and a vaccine reovirus strain were compared for invasiveness, virulence and pathological characteristics upon infection of day old specific-pathogen-free chicks by the footpad, s.c., and oral routes of inoculation. No significant differences were noted regarding the ability of individual isolates to infect target tissues. Virulence (measured as the LD50) among the isolates varied markedly from 2 .times. 105 to < 10 plaque forming units/chick for the most virulent isolate; between the parental wild-type virus and the derivative vaccine virus strain, a 106 difference in virulence was demonstrated. All strains revealed, with considerable variation, arthrogenic potential.